Strictures on Volcanos and Earthquakes. 51 
_ _— appa oA on ae en, of Mr. Joseph Du 
Comm n Volcanos and Earthquakes ;* by Brnsamin 
Bett, of ‘Clietiaineidl Mass. 
TO MR, JOSEPH DU COMMUN, — 
Sir—In accordance with your opinion, as well as with 
that of Dr. Franklin, Mr. Perkins and others—I will allow 
that atmospheric air can be compressed to such a degree as 
to be heavier than water; and that if forced down by means 
of a bell lower than twenty five thousand six hundred feet 
below the surface of the sea, it may stay there, for the present, 
or may fall to the bottom. We will suppose the lowest 
depth of the fee water to be found at the precise point of 
twenty five thou sand six hundred feet from the surface, 
which, for brevity, I shall call the separating point; and that 
a stratum of condensed air occupies the space between that 
point and the liquid Onrgee below, a gallon of which stratum 
eing heavier than a gallon of sea-water. Atthis point of 
contact (separating pont) nae air (see page 16, line 30) must 
e, as you say, “exact the same density with the water.” 
But what would be the Seas of a bubble of air, if con- 
veyed by the bell and left one foot above the separating point? 
As this bubble would have a density tess than the air at the 
separating point, it must rise to the surface ; it cannot fall, 
or, as you say, “shower through the water.” 
If then a bubble of ai r rises, when formed or left one foot 
above the separating point, it may be fairly asserted that it 
would rise if Phomey one inch, or even ;1, of an inch above 
it. To maintain this gaseous stratum then, it is necessary 
to suppose, that the evolution of gas from the water is made 
precisely at the separating point, and that air bubbles (i. e. 
air surrounded by a liquid) are not formed. 
But what should cause a separation at all? The air held 
in solution near the separating point ought to be combined 
with some degree of a. else it would be likely to separ- 
ate béfore it was carried there. Supposing however, that 
it arrives down to the point, there is a great objection to its 
separating at that precise point, in preference to a quarter 
of an inch above ; for no chemical attraction between the 
* See Vol. XV. No. 1. Art. iii. of this Journal. 
